c
(c) In insulators, the electrons are tightly bound with the nucleus hence, at room temperature thermal energy is not enough to push the electrons into conduction band and hence, no electrons are available for conduction. The energy required for electron to escape out from orbit and to over come the energy gap is thus of the order of \(6 e V\), while for semiconductors and conductors it is (of the order of \(1\) eV and \(0\) respectively.